


For Centuries

by mirandamyth



Series: Sidelines [3]
Category: Supernatural
Genre: 10x22, Alternate Universe, Alternate Universe - Canon, Alternate Universe - Canon Divergence, Dean kills things, End of the World, Episode: s10e22 The Prisoner, Gen, Implied Castiel/Dean Winchester, Mark of Cain, Mostly implied violence, No Sex, Torture, but not graphic, it's actually pretty obvious if you read the series, just a little bit, little mad because this series started so happy and is ending with so much angst, moc!dean
Language: English
Status: Completed
Published: 2016-03-02
Updated: 2016-03-22
Packaged: 2018-05-22 14:19:22
Rating: Teen And Up Audiences
Warnings: Major Character Death
Chapters: 2
Words: 2,403
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6082554
Author URL: https://archiveofourown.org/users/mirandamyth/pseuds/mirandamyth
Summary: <blockquote class="userstuff">
              <p>"Maybe you could fight the mark for years, maybe centuries like Cain did. But you cannot fight it forever, and when you finally turn, and you will turn, Sam and everyone else you love, they could be long dead. Everyone except me. I'm the one who will have to watch you murder the world, so if there is even a small chance I could save you I won't let you walk out of this room."<br/>Wherein Death was never an option.</p>
            </blockquote>





	1. Chapter 1

"Maybe you could fight the mark for years, maybe centuries like Cain did. But you cannot fight it forever, and when you finally turn, and you _will_ turn, Sam and everyone else you love, they could be long dead. Everyone except _me_. I'm the one who will have to watch you murder the world, so if there is even a small chance I could save you I won't let you walk out of this room." Cas fights the uncertainty out of every syllable, not ready for the inevitable brawl. Dean has always been more skilled in physical combat, never having had the luxury of grace, and has always been capable of besting him in an even match. With the power of the mark, and Castiel's own diminished grace, he knows he stands very little chance. His only hope is that Dean has enough of himself left to spare Castiel's life.

As Cas lays on the floor with blood blurring his vision, his blade shines clearly, and beyond that, Dean's retreating back. He allows his grace five minutes to heal his vessel, five minutes in which he feels nothing but a deep, hollow sorrow, and knows that next time he will need to be the one plunging the blade, the one faced with the choice: life or mercy. To leave Dean alive would be the truest of tortures for the soul inside of him.

Cas cleans up before leaving the bunker, meticulously putting Dean's room back together.

                                                                                                                 °°°°°°°°°°°°°°°°

Dean hunts alone for a while; mostly werewolves and wendigoes, things that can be called animal attacks, unleashing the wrath of the mark in caves and backwoods. Staying away from Kansas, from what he's increasingly calling his past life. He stops talking to Cas, Crowley, Sam. He destroys his cell phone, starts using new aliases, makes himself disappear.

Two months after his disappearance, Dean starts to feel the edges of himself beginning to fray. It's harder and harder to stop and he looks for stronger enemies, managing to ferret out the very last of the Leviathan. Starts to whisper prayers into the steering wheel, still covered in the blood of his kills. The first time,  just a few words, _Keep Sam alive, I'm sorry._

Dean starts taking his time, working into his prey with his fists before dealing any death blows. He dreams of rivers of blood, of it pouring from the sky like rain; he dreams of Purgatory, of letting the mark do its work, of enemies that just keep coming. He dreams of death and oblivion. He calls for Cas in his sleep now, that long ago bond crying out to be pulled from perdition once again

                                                                                                                °°°°°°°°°°°°°

Castiel hears every word, but he doesn't tell Sam. Rowena had double crossed Sam — deliberately giving him an impotent weapon, hoping her son would finish him off, and escaped with the book and codex. Castiel fears that, should Sam know that Dean had opened a line of communication, he would stop at nothing to find him. Sam grows increasingly desperate, plundering the Styne estate, breaking into Cuthbert Sinclair's invisible hideout, looking for some other way to break the curse.

Cas does his best to honor Dean's wishes, and is usually not far behind Sam. Dean's prayers grow longer, become confessionals, a cross Castiel is willing to bear, if it helps Dean retain his humanity. He begins training his vessel for the fight that's coming. He has to steel himself to kill the man who taught him what it was to love, to be free, to be alive.

                                                                                                                 °°°°°°°°°°°°°°°

Sam pushes forward, hunting down every lead on Rowena and the book, calling in every favor he has, and it still isn't enough. He hunts Crowley down, sure he helped his mother escape. The king disembowels him slowly, cauterizing the wound, ensuring that infection will take Sam, not the mercy of blood loss. Castiel arrives after Sam has been strung up by the wrists, stomach cut and burnt open, intestines stretched to their full length, still attached but not in their right place. He's hazy and on his way to unconsciousness when Cas finds him, and he begs Castiel to let him die.

Instead, he is healed and brought home. Sam stops accepting Castiel's calls, starts ignoring his presence. He tries to sell his soul in exchange for the mark's removal and is laughed at by six crossroads demons before burying his knife into their guts. He hunts for spells that will let him take the mark from Dean without consent. For a way to transfer the curse on to someone else, anyone else. 

                                                                                                                 °°°°°°°°°°°°°°°

Castiel watches the two people he's closest to in the world unravel. Dean from the mark, and Sam from losing his brother. He watches as they both tear their worlds to ruination, travels behind them both, cleaning up where he can. Cas heals Sam repeatedly, often in his sleep, after he's pushed too far, fought too hard. He trails behind Dean, altering and erasing memories where he feels he must. The victims Dean saves are all shell shocked when Cas arrives, not asking questions, just staring at the blood or the raw wood where doors have been forcefully removed from their hinges. Castiel heals them, taking their memories, and returns them somewhere familiar.

Castiel realizes that he is not the only one on this bloody trail. At least one demon is ahead of him, maybe three or four. He knows the activity isn't going to go unnoticed for long, and he is on the lookout for humans who may put themselves in the line of fire. He watches for Sam, especially. The last thing he wants is to come across Sam's body, hacked to bits by Dean's hands.

                                                                                                                 °°°°°°°°°°°°°

Sam's actual demise comes a little more than a year later. Metatron, enraged that Sam did not possess his grace, thrusts a blade through Sam's eye and scrambles his brain. Castiel sends word to Dean, and the location of the pyre. The thing that shows up is a sad excuse for Dean Winchester. Too much anger, not enough grief; not quite demonic, but straddling the line dangerously.

Cas realizes that if he is attacked, there is no guarantee Dean will leave him alive. Where Hell had failed, the mark excelled; Dean's soul, once a beacon which had drawn Castiel into the depths of Hell, was now diminished. To Castiel's relief, Dean doesn't tarnish the memory of his brother with violence. Instead, he buys Cas a beer.

"I know you've been followin' me." Cas is silent, but Dean continues, "S'fine, we both know I got no problem talking to you without an answer." He takes a long pull off his bottle, "But I do need you to tell me who did this to Sammy."

"Metatron." Castiel knows what will happen next, but he wants it to happen. He's just relieved to not have to do it himself.

Dean slaps a ten on the bar and walks out without a word. It only tales him two weeks to track down and dismember Metatron. Castiel looks upon the carnage with a feeling akin to joy.

After Metatron, Castiel finds no bodies, no evidence of Dean. Just the Impala parked outside the empty bunker, and a note.

_Cas,_

_Sam's death was my fault, not yours. I never should have left him alone._ _The bunker is yours, I can't be here, too much of Sammy is. I'm fighting the mark,_ _didn't take any of the weapons, I think Cain had the right idea, the simple life,_ _you know? I'm going to take a leaf out of his book. Don't look for me._

Castiel does look, but finds nothing. Even Crowley can't find Dean. Castiel is eventually called back to Heaven, and decades pass on Earth. Dean doesn't even so much as pray. Castiel keeps an eye on the bunker, even as brambles grow around the entrance, as the car fades into disrepair. He never stops searching, and for almost two hundred years, he finds nothing. Then it starts. A few Djinn are found dead in Chicago, sparking tensions among the monster families. When two shifters are found, the war begins, each family accusing the other; for the murders, for inciting war. More bodies turn up, human and monster, until all the great families fall, and one man stands. Dean Winchester. Just as quietly as he came, he fades away. Castiel arrives and Chicago is burning; there are no survivors to question, no trail to follow. He revisits the bunker, finding it as he left it, and is once again recalled to heaven.

                                                                                                               °°°°°°°°°°°°°°

After the fall of Chicago, there are riots, protests, militants, assassinations. No one has any answers. War breaks across the globe.  Castiel spends much of his time watching for Dean. He knows the warring factions will be calling to the mark, and he worries Dean will not be able to resist. The man in question is keeping bees. He has aged in mind, but not in body. He hasn't killed since Chicago, but he can feel the bloodlust growing. He doesn't know how the bees help, but they do. He lasted two hundred years the first time, but every time he turns on the radio there's news of death and violence, so close. And everything in him is calling for him to pick a side and let blood run the streets. He knows when the front reaches him, bees won't be enough.


	2. Chapter 2

_I'm not doing great down here. Even Cain didn't last this long. It's hungry, Cas. I can feel it, feel what it wants, what it wants me to be. I want it to, I want to let it take hold again. I've been fighting alone for so long. My soul and my sins to bear, but I'm not sure I still can. Sometimes I think Cain was right, and it is better to give in; the world's already gone to hell, Sammy's gone, what have I got left to fight for? Then I remember. You're up there, now, aren't you? Watching over the world, watching out for me. I hope you're ready to kill me, Cas. I hope you've found a way. Because I'm ready to die. I'd hoped I would in Chicago, I thought you'd see that it was me sooner. Maybe I've always given you more credit than you deserve. So this time I'm gonna make it real obvious._ Dean closes the worn and tired journal. It's been with him for the better part of three hundred years, full of one sided conversations with Castiel.

Two hundred and seventy-five years, thirteen days and six hours after Sam's death, Dean finishes the repairs on the Impala. When he feels that distinct disturbance of the air around him; that faint ozone and lightning scent of Castiel; relief floods his body, momentarily erasing the rage and anguish that have taken hold.

"Honey, I'm home." He turns, wiping his hands, devil may care grin on his face. "How ya been, Cas? Still livin' it up in Heaven?"

 "What are you doing, Dean?"

"Thought it was obvious, I'm getting my baby back."

"I've been looking for you for two centuries, Dean. The car has been here for all that time. So the question is, what do you need it for?"

"Whatever I fucking want, Cas." His eyes flash black and chains engraved in Enochian lift from the ground to trap Castiel. "And there's not a damn thing you can do to stop me."

"I was in Chicago. If you could stop the mark after that level of depravity, I believe you can keep doing it. You're strong Dean. Stronger than Cain. You can still do the right thing."

Dean laughs, full of malice. "I've spent the last two centuries doing exactly that. I think it's time I get to have a little fun. I think I deserve it, don't you?" He turns and opens the trunk, selecting a blade. "Now, you have my favorite toy, and I intend to get it back."

He draws the triangular blade quickly across Castiel's throat, catching the grace that spills out in a jar. "So I'm going to ask you nicely, first. Where is the first blade?"

"You're better than this, Dean. You don't have to hurt me."

Dean falters, dropping the blade, "You're right, Cas, I-I don't." He swings, catching Castiel in the jaw, "But, you see, _this_ is what I wanted."

                                                                                                                   °°°°°°°°°°°°°°°°

Castiel remains silent for two days; Dean alternates between blades and fists, healing him intermittently with sips of his own grace. When he breaks, Dean backs away. He slumps in his chains, dripping blood into the small puddle at his feet. Dean places his grace on top of a beaten notebook, and disappears.

Exactly seventeen minutes pass between Dean leaving and Castiel's release from the chains. He falls bodily to the dirt and crawls to retrieve his grace. Power floods him, healing his body, but his heart aches. Dean has obviously been busy; that kind of power doesn't come easy. He was ill-prepared, allowing hope to make him the fool. He pockets the journal as an afterthought.

                                                                                                                   °°°°°°°°°°°°°°

Every where Dean goes people are fighting ― where he walks, there are battlefields; where he stays, there are revolutions. He becomes something of a people's hero as the tyrannical regime falls and new countries form from the wreckage. He fights with the most passionate, those who fight for their cause, even as he fights to quench his bloodlust. He joins the occasional revelry; takes the occasional lover, but largely, he is alone.

                                                                                                                  °°°°°°°°°°°°°°°°

Castiel is woefully blinded by his belief in Dean; a foolish hope that the soul of the righteous man would always be a beacon in the darkness. He follows behind Dean, performing small miracles and gathering information. In two centuries, the world had taken a turn for the worse — there were battles that no one returned from, and Castiel walks through the carnage, eyes closed, lying to himself about the culprit. He reads the journal slowly, trying to understand exactly what happened. Much of it is anger and depression screaming from the page; but there are other entries, whole pages, of memories and nostalgia.

Cas mourns for Dean as he reads. The prayers are painful, full of abandonment and anguish; the memories, full of love and joy, are much more so. Castiel weeps under the stars — for Dean, for himself, for Sam, for the world.

**Notes for the Chapter:**

> Thanks for reading! I just felt like this needed to be written, Cas's speech was too good. Please let me know what you think!
> 
> Also thinking of maybe adding to the series ― maybe some of the journal entries, or maybe with a final encounter. But one of them would die and I can't bring myself to kill Cas. Or Dean. Or I'll post some that fall between this and Battered Books.


End file.
